Well it is nearly 4 months since I made that sausage and the guy I gave it to ate it anyway earlier this week and said it tasted great and he didn't get any ill feelings at all. So I now know that cooked sausage will last 4 months in the fridge if vacuum sealed, the correct amount of cure was used and it was cooked to above 150F.

Just thought I'd share this as I was afraid to eat it after a month :-)